1. Field of the Invention
The present invention relates to a technique for identifying the four corners of a rectangular image in which a code is embedded when the image is pictured and imported.
2. Description of the Related Art
Conventionally, a rectangular image in which a code is embedded (simply noted as “rectangular image” hereinafter) is printed, or electronically displayed, on a medium, then the image is imported by photographing the rectangular image on the medium with a portable phone equipped with a camera (noted as “camera phone” hereinafter), the code, which is embedded in the rectangular zone using an electronic watermarking technique, is read and the information corresponding to the code is displayed on the screen of the portable phone.
In such a process, a frame is provided on the outside of the rectangular zone, or a mark is provided therein, in order to identify the section in which the imported rectangular zone exists.
As an example, a rectangular image is provided with three or more cross- or L-shaped positional detection marks, as shown in FIGS. 1 and 2, according to reference patent document 1. Meanwhile, a rectangular image is provided with a frame (in a prescribed color) in order to identify the zone of the rectangular image, as shown in FIG. 3, according to reference patent document 2.
The conventional techniques are faced with the problem of degrading appearance because the rectangular image is provided with a mark or frame.
Patent document 1: Laid-Open Japanese Patent Application Publication No. 2005-293409, “SPECIFIC IMAGE POSITION ESTIMATING DEVICE, SPECIFIC IMAGE POSITION ESTIMATING METHOD, SPECIFIC IMAGE POSITION ESTIMATING PROGRAM, RECORDING MEDIUM COMPUTER-READABLE WITH SPECIFIC IMAGE POSITION ESTIMATING PROGRAM STORED, AND MEDIUM”
Patent document 2: Laid-Open Japanese Patent Application Publication No. 2003-110845, “IMAGE PROCESSOR, ITS CONTROL METHOD, COMPUTER PROGRAM AND RECORDING MEDIUM”